Lead Backend Engineer (Java)
FlintN is looking for a Lead Backend Engineer (Java) to join the team, which is building and scaling an all-in-one payment platform for online businesses. The role focuses on product development, testing, and integrations aimed at building a global payment platform.
The successful candidate will own the technical direction of one or more backend domains, including payments, routing/cascading, subscriptions, and chargebacks. This involves managing architecture, roadmaps, and technical debt strategies. The role also includes leading a team of backend engineers through task decomposition and planning, code review, mentoring, 1:1 technical guidance, and onboarding of new hires. The engineer will design and drive the delivery of distributed, high-throughput, fault-tolerant services and their APIs for internal teams and external integrations. Ownership of service quality in production is key, including SLOs, observability coverage, alerting, on-call rotation, incident response, and postmortems. The role also encompasses owning the release process for the domain, ensuring safe migrations, rollback-compatible changes, and sandbox/production validation.
- Own the technical direction of one or more backend domains (payments, routing/cascading, subscriptions, chargebacks) - architecture, roadmap and technical debt strategy.
- Lead a team of backend engineers: task decomposition and planning, code review, mentoring, 1:1 technical guidance, onboarding of new hires.
- Design and drive delivery of distributed, high-throughput, fault-tolerant services and their APIs for internal teams and external integrations.
- Own service quality in production: SLOs, observability coverage, alerting, on-call rotation, incident response and postmortems.
- Own the release process for your domain - safe migrations, rollback-compatible changes, sandbox/production validation.
- Strong system design skills - able to own the architecture of a payment domain end-to-end: API contracts, data model, failure modes, idempotency, consistency guarantees, capacity and cost (required).
- Deep Java (17/21) and Spring Boot 3.x expertise; confident with concurrency, transactional boundaries, retry/backoff strategies and graceful degradation (required).
- Production experience with event-driven architecture on Kafka - topic/partition design, ordering and delivery guarantees, consumer scaling, DLQ and replay, backward-compatible event evolution (required).
- Advanced Postgres expertise - data modeling, indexing and query tuning, locking, zero-downtime and rollback-safe schema migrations (expand/contract) (required).
- Experience running services in Kubernetes/AWS (EKS, MSK, RDS, S3, IAM); comfortable reading Terraform and Helm and reasoning about a GitOps delivery pipeline (required).
- Experience with analytical/OLAP storage (ClickHouse, Opensearch or equivalent) - understand the trade-offs of a dual-path (OLTP + analytics) data flow (required).
- Treat observability as an engineering discipline: metrics, structured logs, distributed tracing, meaningful SLOs and alerts (required).
- Strong payments domain expertise: authorize/capture/void/refund lifecycle, 3DS and challenge flows, chargebacks and disputes, PSP/acquirer integrations, routing and cascading, subscriptions and MIT/recurring billing, tokenization, PCI-DSS constraints (required).
- Practical security mindset - handling of card data, secrets management, least-privilege access, audit trails (required).
- Ownership of engineering processes: code review culture, TDD/BDD, test pyramid (unit / integration / e2e), CI/CD, release and rollback procedures, incident management and postmortems (required).
- A chance to work on an early-stage payment product.
- Opportunity to make architectural decisions, work with AI and high-level engineering, enjoy technical freedom, and directly influence the product’s development vector.
- The startup drive - backed by the stability and support of a holding company.
- From idea to action - minimal steps. Any proposal can turn into real changes in the product or processes.
- Your office is wherever it’s convenient for you: home, our Kyiv office, coworking spaces in Lviv or Warsaw, or anywhere else with a stable Wi-Fi connection.
- Flexible working hours. Plan your day for maximum efficiency: start between 8:00 and 11:00 and finish between 17:00 and 20:00, considering team collaboration hours.
- Continuous growth is a must. Courses, conferences, and an internal library - we invest in your development because the team’s speed and performance directly depend on the expertise of its people.
- Health care and wellbeing: medical insurance, a Mental Health program, and compensation for sessions with a psychologist.
- Time to recharge: 28 paid days off per year, sick leave, and all public holidays fully covered.
- Gifts for special occasions.
- Social Impact. The Ukrainian Victory Support program and other charitable initiatives supporting Ukraine.
- An active corporate life: quarterly team buildings, workshops, and other holding-level events.
Boosta is an international IT company that develops and promotes SEO tools, digital products and educational products, primarily for Western markets. Founded in 2014 and headquartered in Kyiv, Ukraine, it has released more than 10 products used by tens of thousands of people across Europe, Asia, the Americas and Australia. The company employs a team of over 400 specialists and runs an R&D department that backs startups and develops new products. Boosta operates across several verticals, including the iGaming affiliate space.
